Means for preventing reverse flow from branch lines to supply mains



'Aug.31,1943. B EIAHLP'RT I 2,328,118

MEANS FOR PRVENTING REVERSE FLOW FROM BRANCH LINES TovsUPPLY MAINS Fil'ed Dec. 9, 1940 2 Sheets-'Sheet l il piggm Aug. 31, 1943.

MEANS FOR PRVENTING -REVERVSE FLOW FROM BRANCH LINES TO SUPPLY MAINSl v Filed Deo. 9, 1940 2 Sheets-Sheet 2 B E AHLPORT 2,328,118

Patented Angri, `1943 MEANS FOR PRWENTING REVERSE LINES TO SUPPL FROM BRANCH Brodie E. import, Los Angeles, Calif. Application necembere, 1940, serial No. 369,220 y1,1 claims. (ci. zii-io) A .l p e companying drawings for an illustrative `'embodie devices for preventbranch conduits to supply 'I'his invention relates to ing reverse flow from mains. v i

An object of the invention is to provide a device adapted to be installed in a branch pipe Vor conduit adjacent the supply main which will prevent siphoning or reverse flow from the `branch line to the supplymain in the event that pressure in the supply main falls below that in the branch line. In certain water main installations if the pressure in the water main falls due to unusually heavy withdrawals of water or breaks occurring l therein, there is danger of siphoning water back into the main from the branch lines connected thereto. back through the branch lines and in other instances it may flow from the branch line to the water main by gravity. In either event thereu is danger of pollution of the Water in the Water main.

It has heretofore rate check valves in been proposed to incorpothe branch line or conduit that would prevent reverse ow. However, as the occasions when the pressure in the water main is less than the pressure in the supply line are relatively rare such check valves seldom have occasion to seat and consequently are apt to lea'k when called upon to prevent reverse flow. It has valso been proposed to incorporate in the branch line anti-siphoning devices which vserve to prevent siphoning action by the admission of air. Such devices are subject to the objection of admitting air to the main which might pollute to a limited extent only and in the case of gas mains would be seriously objectionable intthat by admitting air to the main an explosive mixture of air and gas would be apt to be formed.

An object of the present invention is to provide a construction which is operable in response to the pressures in its inlet and outlet to prevent reverse now from the branch line to the main Without admitting air and without presenting a danger of polluting the iluid conducted by the main.

Another object is to provide a device wherein the valves are positively operated under the influence of pressure so that even though the valves may not be seated over a long period of time, yet when they are called firmly seated against their seats to prevent leakage.

With the foregoing and other objects in view, which will be made manifest in the followin detailed description and specifically pointed out in the appended claims, reference is had to the ac- In some instances water is siphoned upon to act they will be `form of construction;

YMAINSf:A

ment of the invention fwlierein: i V

Figure 1 is a sectional view throughonedevice embodying thel invention, this being the preferred Fig. 2 isa sectional view through the device embodying-an alternative form that maybe employed; and 1 y Fig. 3 is a sectional view through still another alternative form embodying the' invention.

Referring to the accompanying drawings wherein similar reference characters indicate similar parts throughout, the device illustrated in Fig. 1 comprises a suitable body Il) adapted to be mounted or incorporated in a branch line or conduit preferably adjacent its connection with the supply main. This body has aninlet indicated at I I leading from the main and an outlet I2 leading to the branch line. Adjacent the inlet II there is a valve seat I3 for a valve I4, the stem of which, indicated at I5, is slidably guided by means of a valve guide formed on a plug I6. A metallic bellows Il connects the back of the valve I4 with the inner side of plug I6. Any equivalent pressure responsive means such as for example a piston ordiaphragm could be used in substitution for the metallic bellows I1 and the other metallic bellows hereinafter described. The interior of the bellows is adapted to be supplied with iiuid pressure through a tube I8 connected to ,plug I9 adjacent the outlet I2. Ports 20 are formed in the plug I9 for the purpose of conveying the pressure present in outlet I 2 through tube I8 and through ports 2| to the interior of the bellows.

Adjacent the outlet I2 there is formed a seat 22 for a check valve 23 the stem of which'is guided by a stern guide formed on the underside of plug I9. The two valves I4 and 23 constitute check valves arranged in series between the inlet i I and the outlet I2 and in the passage through the body I0 that connects the inlet with the outlet. e

Adjacent the center of the body there is a valve seat 24 for a normally closed drain valve 25. The drain valve 25 has its stem guided by a guidefon the underside of a. plug 26 which is ported as at 21 and is equipped with a metallic bellows 28"... A tube 29 connects the hollow interior of plug 25 with an apertured plug 30 so that pressure at the inlet II is conveyed through the tube 29 to the to urge the valve 25 to seat or to remain closed.

Adjacent the bottom of the bod'y there is a plug 3| ported as at 32 and yproviding a guide for a stem 33 which is equipped with a metallic bellows interior of bellows 28to expand the bellows and,

within bellows 28 it is elective to open valve` 25. j.

A branch tube 35 leads from tube I8 to the in# terior of bellows 34. A drain outlet 36 leads from the bottom of the body Ill and may have a drain tube, 'not shown, connected thereto. The bellows .28 and 34 are soconstructed and arranged that whenever the pressures therein are equal. the drain valve 25 will be closed so that the drain valve is initially in closed position.

The operation of the above-described construction is as follows. Normally the pressure in the inlet I I will be equal to or greater than the pressure in outlet I2. Under these circumstances whenever the pressure in the inlet II is greater than the pressure in the outlet I2 it is eilective to open valves I4 and 23 permitting iiow from the supply main to the branch line. However, if for any reason pressure in the outlet I2 should become greater than the pressure in the' inlet II so that there would be a tendency for reverseI now, valve 23 would tend to seat by gravity. However, in the event that this valve should leak it is important to prevent contamination in the supply main.- Consequently, the excess of pressure in the outlet I2 is transmitted through tube I8 to the interior of cause valve I4 to close. Asv there might possibly be some leakage between valve I4 and its seat provision is made for draining out of the device all fluid between the two check valves. To this end the outlet pressure at I2 on being transmitted to the interior of bellows 34 andbeins greater than the inlet pressurev transmitted to the interior of bellows 28,v bellows 34 becomes effective to open or unseat the drain valve 35 permitting iluid between the two valves I4 and 23 to drain through the drain outlet 36. Consequently, if valve 23 should leak the leakage is drained out of the construction so that there is no opportunity for leakage to flow back into the main past valve I4. The opening yof the drain outlet also interposes a protective air space between fluid in the main and fluid in the branch line and in addition eilects a sudden and complete 'drop in pressure in back of the outlet valve which aids in its closing with a positive snap action, thus wire drawing and chattering are effectively pre- 'vented and the outlet valve is urged to firmly seat.

Whenever normal conditions are restored so that the inlet pressure exceeds the outlet pressure valves I4 and 23 open and as the pressure within bellows 28 exceeds the pressure within bellows -34 the drain valve 25 again closes restricting flow from the inlet to the outlet and permitting none of it to pass to the drain outlet 36.

In Fig. 2 an alternative form of construction is disclosed wherein the body 40 an inlet 4I and an outlet 42. Within the body there are two check valves 43 and 44 arranged in series. 'I'he check valve 43 is equipped with a metallic bellows 45 which is supplied with internal pressure through tube 36 from the outlet 42. The4 drain outlet is indicated at 41 Aand the drain valve is indicated at 48. The drain valve is equipped with a. bellows 49 which is supplied'v with internal pressure equal to that at the inlet through tube I). A stem 5I is equipped with a bellows 52 internally supplied with pressure through a branch tube 53 equal to the pressure adjacent the outlet 42. In this form is equipped with the valves 43 and 44 and of construction it will be noted that the exposed area of the drain valve when seated is subject to the pressure that may be in the body 40 between that this exposed area is greater than the area exposed on the bottom of stem 5I within the bellows 5,2. The two bellows 52 and 48 are of the same diameter. The

' purpose of this construction is to cause the drain between the two valves 43 and 44 is in excess'of bellows I1 and is effective to l I on its interior iluid pressure valve 48 to open not only when the pressure at the outlet 42 is in excess oi the Apressure at the inlet 4I but also when the pressure in the body Under normal conditions when the inlet pressure is in excess of the outlet pressure, valves 43 and 44 will be forced open by the inlet pressure and the drain valve 48 will be forced closed by the inlet pressure in bellows 49 being greater than the outlet pressure in bellows 52. Whenever the outlet pressure exceeds the inlet pressure, however, valve 44 closes and the outlet pressure is conveyed to the interior of bellows 45 causing valve 43 to close. At the same time outlet pressure is conveyed to the interior oi bellows 52 and thisbeing in excess of the inlet pressure in bellows 49, the drain valve' 48 will open permitting drainage outlet 41. The drain valve 48 will also open whenever the pressure between valves 43 and 44 is in excess or the inlet pressure. The pressure between the valves 43 and 44 being effective on the exposed surface of valve 48 urges this valve' to open overcoming the lower pressure of the inlet which is within bellows 49.

In Fig. 3 there is illustrated another form embodying the invention wherein the body 55 has the inlet pressure.

an inlet 56, an outlet 51, and a drain outlet 58.

Adjacent the inlet there is a main valve 59 influenced by a metallic bellows 66 which receives from the outlet 51 through a'tube or conduit 6 I Adjacent the main valve 59 there is an auxiliary valve 62 which is also iniluenced by a bellows 63 which receives in its interior fluid pressure from the tubing or conduit 6 I.l The auxiliary valve 62 which may be regarded as a type of pilot valve and the main valve 59 control the flow from the inlet 56 to a lower chamber 64 which in turn leads to the outlet 51 past a check valve 65. Adjacent the drain outlet 58 there is a drain valve 66 iniluenced by a bellows 61 the interior of which is in communication with the inlet pressure at 56 by means of a tube or conduit 68. The valves 62 and 66 operate in unison and in opposition to each other and to this end may be connected by a connecting rod 69. In some instances this connecting rod may be fastened to one valve and merely bear upon the other.

The operation of this form of construction is as follows. Whenever the inlet pressure 56 is in excess of the outlet pressure at 51, the inlet pressure which is transmitted to bellows 61 is eiective to close valve 66 and openvalve 62. The pressure within chamber 64'will then be equal to the inlet pressure by virtue of valve 62 being open and this pressure being in excess of the outlet pressure at 51 and consequently the pressure within bellows 66 will open the main valve 58. When, however, conditions are such that the pressure at the outlet 51 is in excess of the pres'- sure at the inlet 56 this is eiective to cause bellows 63 to close valve 62 and open valve 66 with the result that the pressure in chamber 64 quickly reduces to atmospheric pressure if outlet 58 merely leads to the atmosphere. If the drain to take place to the drain outlet It leads tosome other locality of reduced pressurev the pressure at BI isy quickly reduced to this reduced pressure. Consequently, by suddenly reducing the pressure in chamber 64 by opening valve 88 the check valve 85 is urged rmly against its seat and likewise the pressure at outlet l which is present in bellows 60 being unopposed is similarly forced firmly against its seat.

'From the above-describedl constructions it will be apprecated that a device has been provided which will eiectively prevent reverse ilow from a branch line or conduit to a supply main. Two check valves are employed to prevent this reverse ilow which ii either orboth leak, are adequately protected by the opening of the drain valve to prevent leakage back into the supply main. Con-` tamination of the iluid in the supply main is thus completely prevented. AlthoughAI have illustrated the connections for conveying the inlet and outlet pressures as being formed by tubing arranged externally ot the body it will of course be appreciated that corresponding passages may be formed by drilled or cored passages formed in the body itself. y

-Variouschanges may be madel in the details of construction without departing i'rom the spirit or scope oi' the invention as defined by the appended claims.

I claim:

1.A device of the class described comprising a body having an inlet and an outlet, two check valves arranged in series in the body between the inlet and outlet, a drain outlet between the check valves, a drain valve normally closing the drain outlet, pressure responsive means subject to pressure in the inlet ahead of the check valve therein urging the drain valve to close, and pressure responsive means subject to pressure in the outlet behind the check valve therein urging the drain valve to open, said pressure responsive means being so constructed and arranged that when the pressure in the outlet exceedsl the pressure in the inlet the drain valve will be opened.

`2. A device of the class described comprising a body having an inlet and an outlet, two check valves arranged in series in the body between the inlet and outlet, a drain outlet between the check valves, a drain valve normally closing the drain outlet, pressure responsive means subject to pressure in the inlet urging the drain valve to close, pressure responsive means subject to pressure in the outlet urging the drain' valve to open, and

pressure responsive means subject to pressure in the outlet urging the check valve most adjacent the inlet to close whereby when pressure in the outlet exceeds the pressure in the inlet the drain valve will be opened and the check valve most adjacent the inlet will belclosed.

3. A device of the class described comprising a body having an inlet, an outlet, and a drain outlet,'a bellows closed valve adjacent the inlet controlling ilow therethrough, means conveying pressure from the outlet to the bellows to urge the valve to close, said valve being capable of being opened by inlet pressure exceeding the outlet pressure, a normally closed drain valve controlling the drain outlet, and pressure responsive means subject to the pressures in the inlet and outlet for causing the normally closed drain valve to open whenever the outlet pressure exceeds the inlet pressure.

4. A device of a body having an inlet, an outlet, and a drain outlet, a bellows closed valve adjacent the inlet controlling now therethrough, means conveying the class described comprising pressure from the outlet to the bellows to urge the valve to close, said valve being capable of being opened by inlet pressure exceeding the outlet pressure, a normally closed drain valve controlling the drain outlet, pressure responsive means subject to the pressures in the inlet and outlet for' causing the normally closed drain valve to open whenever the outlet pressure exceeds the inlet pressure, and a check valve preventing reverse flow through the outlet.

5. A device of the class described comprising a body having an inlet an outlet, and a drain outlet, controlling flow therethrough, means conveying pressure fromv the outlet to the bellows to urge the valve to close, said valve being capable of being opened by inlet pressure exceeding the out'- let pressure, a normally closed drain valve controlling the drain outlet, bellows means subject to inlet pressure urging the normally closed drain valve to close and bellows means subject to outlet pressure urging the normally closed drain valve to open whereby it may open whenever the outlet pressure exceeds the inlet pressure.

6. A device -of the class described comprising a body having.an inlet,

pressurev from the outlet to the bellows to urge the valve to close, said valve being capable of being opened by inlet pressure exceeding the outlet pressure, a normally closed drain valve controlling the drain outlet, bellows means subject to inlet pressure urging the normally closed drain valve to close and bellows means subject to outlet pressure urging the normally closed drain valve to open whereby it may open whenever the outlet pressure exceeds the inlet pressure, and a check valve preventing reverse ilow through the outlet.

7. A device of the class described comprising a body having an inlet and an outlet, two check l valves arranged in series between the inlet and the outlet, a drain outlet between the check valves, a drain valve for opening and closing the drain by inlet pressure ahead of the check valve therein urging it to close and by outlet pressure behind the check valve therein urging it to open in such a manner that the drain valve will be closed by the inlet pressure whenever the inlet pressure exceeds the outlet pressure and opened by the outlet pressure whenever the outlet pressure exceeds the inlet pressure.

8. A device of the class described comprising a body having an inlet and an outlet, two check valves arranged in series between the inlet and the outlet, a drain outlet between the check valves, a drain valve for opening and closing the drain outlet, pressure responsive means connected to the inlet ahead of the check valve therein so as to be responsive to inlet pressure urging the drain valve to close, and pressure responsive means connected to the outlet behind the lcheck valve therein so as to be responsive to outlet pressure urging the valve to open, said pressure responsive means being so constructed and arranged that the drain valve will be closed by the inlet pressure whenever the inlet pressure exceeds the outlet pressure and openedby the outlet pressure whenever the outlet pressure exceeds the inlet pressure.

9. A device of the class described comprisingl a body having an inlet and an outlet, valves aroutlet permitting a bellows closed valve adjacent the inlet an outlet, and a drain' outlet, a bellows closed valve adjacent the inlet controlling ow therethrough, means conveying outlet, said drain valve being iniiuenced inward new through the met anal outward flow a through the outlet but preventing flow in the reverse direction, there being a drain outlet between Athe valves, a drain valve controlling the drain outlet, bellows arranged upon opposite sides of the drain valve, means for conducting inlet pressure ahead'of the checkvalve in the inlet to that bellows which when subjected to pressure will urge the drain valve to close, and means conducting outlet pressure behind the check valve in the outlet to that bellows which when subjected topressure will urge the drain' valve to open, said bellows being so constructed and arranged that the drain valve will be closed by the inlet pressure when the inlet pressure exceeds the outlet pressure, and the drain valve will be opened when the outlet pressure exceeds the inlet pressure.

vl0. A device of the class described comprising a body having an inlet and an outlet, valves arranged adjacent the inlet and outlet permitting inward flow through the inlet and outward ow through the outlet but preventing flow in the reverse direction, there being a drain outlet between the valves, a drain valve controlling the drain outlet, bellows arranged upon opposite sides of the drain valve, means of conducting inlet pressure to that bellows which when subjected to pressure will urge the drain valve to close, means conducting outlet pressure to that bellows 'a body having an inlet which when subjected to pressure will.urge the drain valveto open whereby the dralnvalve will be closed by the inlet pressure when the inlet pressure exceeds the outlet pressure and the drain valve will be opened when the outlet pressure exceeds the inlet pressure, the valve adjacent the inlet having a bellows connected to the outlet so as to be subject to outlet pressure whereby the valve adjacent the inlet will be urged to close by outlet pressure whenever the outlet pressure exceeds the inlet pressure although the drain valve may be open.

11. A device of and an outlet, valves arranged ,adjacent the inlet and outlet permitting inward flow through the inlet and outward ow through the outlet Ibut preventing ow in the reverse direction, there being a drain outlet between the valves, a drain valve controlling the drain outlet, means responsive to the pressures in the inlet and outlet for causing the drain valve to close whenever the inlet pressure exceeds the outlet, pressure and for causing the drain valve to open when the outlet pressure exceeds the inlet pressure, and means responsive to pressure in the outlet for causing the valve adjacent the inlet to close whenever the outlet pressure exceeds the inlet pressure although the drain valve may be open.

' BRODIE E. AHLPORT.

the class described comprising 

